Cast error warning while testing strlen

[Pafik0000]

Cast warning in tests/ft_strlen_test.cpp (lines 18 and 19)
Adding (char *) cast (as below) fixes the issue

18 |    /* 1 */ check(ft_strlen((char *)"123") == 3); showLeaks();
19 |    /* 2 */ check(ft_strlen((char *)"") == 0); showLeaks();

[Tripouille]

Hi, this doesn't seem like a massive issue, feel free to open a pull request if you're comfortable with this idea.